The present invention is in the field of tractor-mounted rotary blade type cutters used for cutting grass, weeds and other vegetation such as, for example, along the shoulder of a road, railroad rightsofway and the like. More specifically, the present invention is directed to a unique articulated boom supported blade type cutter that can be mounted on a relatively lightweight tractor such as those in the 35-50 HP class without using integral or other counterweights or exceeding the maximum operating weight of the tractor and which is operated by hydraulic fluid provided by pumps driven by the tractor motor. One reason the prior known devices have required the use of larger and heavier tractors is the fact that they have universally employed separate counterweights which serve no purpose other than to counterbalance the weight of the boom and cutter head assembly.
Rotary blade type vegetation cutters have been used on tractors and other vehicles for many years. However, the prior known vegetation cutters have suffered from a number of drawbacks including having excessively high center of gravity and being of excessive weight so as to require their usage with larger tractors, a fact which renders them unusable with smaller and lighter more economical to operate tractors. The excessive weight of prior art vegetation cutters is resultant from their use of counterweights which are made necessary by their high center of gravity and/or ungainly design and configuration.
Another problem with the prior known rotary blade vegetation cutters has been that many of such cutters have employed a chain drive power transmission to the cutter blade which creates substantial and expensive maintenance and safety problems including the fact that the chain must be enclosed in a housing which adds to the fabrication expense of the device. Proper alignment of the various components of such systems is also difficult to obtain.
An additional problem with tractor mounted prior art rotary blade vegetation cutters is low ground clearance due to the fact that they employ transverse frame members extending beneath the motor of the tractor to connect frame components such as the boom and hydraulic reservoir respectively on opposite sides of the tractor motor.
Yet another problem with the prior known rotary blade type vegetation cutters is that they employ complicated hydraulic circuitry which frequently uses high back pressure in the order of 500 psi in the exhaust circuit and which requires the use of additional coolers for preventing overheating of the hydraulic fluid. Such prior art systems also use bypassing of the hydraulic circuitry to permit stopping of the blade assembly.
Yet another problem with the prior known rotary blade type cutters resides in the fact that they are complicated and consequently the installation on and removal of such cutters from a tractor is time-consuming and expensive. The foregoing problem is all the more critical because of the fact that the cutter must be removed in many instances when maintenance is required for either the tractor or the cutter so that labor and downtime required in such removal and the subsequent reattachment to the tractor is a substantial component of the total operating expense. Many prior art vegetation cutters employ an expensive to fabricate tapered cutter shaft or spindle to which the blade is attached with the cutter shaft being held in position by a threaded nut or similar retainer threaded on a tapered spindle in a manner which, when the cutter shaft is jammed by bearing failure, which can be caused by a variety of events, rotates off and clears the end of the cutter shaft or spindle to cause the spindle and cutter blade to be dropped to the ground to create the need for a time consuming remounting of the blade assembly in the housing.
Another problem with prior known devices in the tractor mounted rotary vegetation cutter art is that the devices do not snugly secure the equipment for over-the-road travel with some devices merely relying upon hydraulic locking of the components in position so that any failure in the "locked" circuit could result in a dangerous release of the equipment. Other devices rely upon mechanical retention of the parts by hooks or other means which can accidentally come loose and release the equipment.
Therefore, it is the primary object of the present invention to provide a new and improved vegetation cutter capable of being mounted on a relatively small tractor.
A further object of the present invention is the provision of a new and improved vegetation cutter that can be easily attached and/or removed from a tractor.
Yet another object of the present invention is the provision of a new and improved vegetation cutter employing hydraulic circuitry operable by hydraulic power at lower pressure than prior known vegetation cutters.
Yet another object of the present invention is the provision of a new and improved vegetation cutter not requiring counterweights for satisfactory operation when installed on a tractor.
A further object of the present invention is a provision of a new and improved blade mount assembly for a vegetation cutter in which the blade does not drop from the assembly upon seizure of a bearing.
Another object of the present invention is the provision of a hydraulically powered vegetation cutter in which shutdown of the blade is effected without hydraulic bypassing of power fluid to permit a rapid shutdown in emergency situations.
A further object of the invention is the provision of a new and improved latch means for holding the components of a vehicle mounted vegetation cutter in a travel position in a secure and safe manner.